1962 London smog
From Tardis Wiki, the free Doctor Who reference
London had a "really bad smog" in December 1962. The Fifteenth Doctor recalled this to 2024 native Ruby Sunday, who had believed that London had gotten rid of its smog in the 1950s. On 11 February 1963 in an alternate timeline, the Doctor realised that what appeared to be smog was in fact Maestro's darkening of the Earth. (TV: The Devil's Chord [+]Loading...["The Devil's Chord (TV story)"])